(1) Field of the Invention
The invention relates to electrically powered centrifugal pumps and is directed more particularly to a combination electrical motor and fluid pump assembly, wherein a single apparatus constitutes both a motor and a pump.
(2) Description of the Prior Art
The traditional electrically driven centrifugal pump assembly includes (1) an electric motor, (2) a pump, and (3) a coupling system for interconnecting the motor and pump. Proper alignment of the three components must be maintained; otherwise, vibrations cause excessive wear and noise, sometimes leading to premature system failure. The motor output is transferred, via the coupling system, to the pump. The pump transfers energy to the fluid flowing therethrough, increasing the velocity and/or pressure of the fluid. The electric current, converted into torque by the motor, produces waste heat, which must be removed by some means, usually by air or water cooling.
In the traditional assembly, the motor, pump and coupling system are arranged in-line axially. The coupling system typically includes shafts, bearings and linkages. Further space may be required for ventilation or water cooling. In areas in which space is at a premium, as, for example, in underwater vehicles, locating a large number of such assemblies in a given relatively limited area can pose severe problems.
Further, in certain motor and pump applications, as for example for pumping liquids in naval torpedoes, the cooling of the pump motor entails weight considerations because the torpedo system is basically designed for a high speed, relatively short (minutes) run, requiring extraordinarily high performance operation and therefore very hot motor operation. In these applications the elimination of the function of cooling the pump motor results in a significant increase in weight payload carrying capacity of the torpedo.
There is thus a need for a motor and pump assembly which requires less space for the motor and pump functions and which requires no external cooling system, thereby further lessening the space needed.